Acid-assisted strategy towards reuse of waste polyimide materials for multi-scenario thermally insulating and high-strength functional applications

Polyimide (PI) has attracted significant attention due to its outstanding comprehensive properties. However, its rigid molecular structure and chemical inertness pose challenges for the effective reuse of waste PI, causing environmental concerns and resource depletion. In this work, we present an acid-assisted sulfonation approach to efficiently reuse waste PI materials. The sulfonated PI (SPI) dispersion produced by this method can be readily processed with water-soluble polymers. For example, the fabricated SPI/sodium alginate composite fibers demonstrate impressive tensile strength (162 MPa) and thermal insulation properties. Furthermore, the resulting SPI/reduced graphene oxide aerogels exhibit a unique combination of high fatigue resistance, low thermal conductivity (0.0276 W m −1 K −1 ) and excellent sensing performance. These findings confirm that this method offers an effective route for repurposing waste PI into value-added products that meet the needs of different specific application scenarios, contributing to sustainable economic development.